Landing gear structures used during takeoff and landing are mounted to airframe of airplane. Typically, the landing gear structures support wheels at lower end portions of main strut members supported on the airframe such that the wheels are rotatable, to allow the airplane to plane on the ground. Since the landing gear structures are required to withstand a load of the airframe during planing on the ground, each main strut member is provided with a shock absorber for absorbing the load. The main strut members are sometimes mounted to the airframe via up-down mechanisms, respectively. In this case, during flying, the main strut members and the wheels are stored into the airframe. Further, each landing gear structure includes several hydraulic devices such as a brake of the wheels and an actuator of the up-down mechanism. Components of the main strut member, the up-down mechanism, etc., are attached with tubes and the like to feed hydraulic oil to these hydraulic devices.
As should be understood from the above, the landing gear structure has a complex configuration including a variety of components. Aerodynamic noise emanating from the landing gear structure is one cause of noise generated from the airplane during takeoff and landing. To attenuate this, a variety of proposals have been made heretofore. For example, a landing gear structure disclosed in Patent Literature 1 includes a fairing for covering the entire of underside and forward side of the landing gear structure. It may be considered that the fairing allows the landing gear structure to avoid direct contact with a high-velocity airflow, thereby attenuating the noise emanating from the landing gear structure. It may also be considered that the fairing serves as a noise-proof wall for blocking the aerodynamic noise emanating from the landing gear structure which would otherwise be transmitted to outside.